PET/MRI and PET/CT in advanced gynaecological tumours: initial experience and comparison.

PURPOSE: To compare the diagnostic accuracy of PET/MRI and PET/CT for staging and re-staging advanced gynaecological cancer patients as well as identify the potential benefits of each method in such a population. MATERIAL AND METHODS: Twenty-six patients with suspicious or proven advanced gynaecological cancer (12 ovarian, seven cervical, one vulvar and four endometrial tumours, one uterine metastasis, and one primary peritoneal cancer) underwent whole-body imaging with a sequential trimodality PET/CT/MR system. Images were analysed regarding primary tumour detection and delineation, loco-regional lymph node staging, and abdominal/extra-abdominal distant metastasis detection (last only by PET/CT). RESULTS: Eighteen (69.2 %) patients underwent PET/MRI for primary staging and eight patients (30.8 %) for re-staging their gynaecological malignancies. For primary tumour delineation, PET/MRI accuracy was statistically superior to PET/CT (p < 0.001). Among the different types of cancer, PET/MRI presented better tumour delineation mainly for cervical (6/7) and endometrial (2/3) cancers. PET/MRI for local evaluation as well as PET/CT for extra-abdominal metastases had therapeutic consequences in three and one patients, respectively. PET/CT detected 12 extra-abdominal distant metastases in 26 patients. CONCLUSION: PET/MRI is superior to PET/CT for primary tumour delineation. No differences were found in detection of regional lymph node involvement and abdominal metastases detection. KEY POINTS: • PET/MRI is superior to PET/CT for primary tumour delineation • PET/CT represents a reliable tool to detect extra-abdominal distant metastasis • PET/MRI might be the preferred imaging modality for staging cervical and endometrial tumours • Whole-body staging for detection and evaluation of extra-abdominal metastases is mandatory.

Indeterminate adnexal masses at ultrasound: effect of MRI imaging findings on diagnostic thinking and therapeutic decisions.

OBJECTIVE: To determine the impact of MRI including DWI on therapeutic decision-making and costs in the work-up of patients with a indeterminate adnexal mass on ultrasound. METHODS: Thirty-eight patients with indeterminate ovarian lesions scheduled for surgery were included in this prospective study. In a questionnaire, the surgeon characterised the lesions based on a morphological score and determined the surgical procedure. The assessment was re-evaluated knowing MR findings and correlated with the final diagnosis. A cost-benefit analysis of MRI was performed. The impact of including DWI in the MR protocol was assessed. RESULTS: MRI provided major diagnostic information in 11/38 cases (28.9%) resulting in abstention from surgery in 5 cases; moderate additional information was recorded in 10/38 (26.3%) patients. Overall a net cost saving (3'676 EUR) was achieved. DWI did not show a significant difference between benign and malignant lesions. Teratomas yielded significantly lower mean ADC values (0.597 × 10(-3) mm(2)/s) compared with all other adnexal lesions (1.812 × 10(-3) mm(2)/s); the mean ADC values in endometrioma (1.387 × 10(-3) mm(2)/s) were significantly lower than in other cystic lesions (2.372 × 10(-3) mm(2)/s). CONCLUSION: Inclusion of MRI in the diagnostic algorithm of the indeterminate adnexal mass allows better differentiation of ovarian lesions resulting in a change of therapeutic decision-making with net cost savings.

Should less motion sensitive T2-weighted BLADE TSE replace Cartesian TSE for female pelvic MRI?

OBJECTIVES: To prospectively compare the diagnostic performance of a non-Cartesian k-space sampling T2-weighted TSE BLADE sequence with a conventional T2-weighted TSE sequence in female pelvic organs. METHODS: Forty-seven patients with sonographically indeterminate adnexal masses or uterine lesions underwent sagittal BLADE and conventional TSE at 1.5 T after glucagon administration. Two radiologists independently determined their preferred sequence by rating: overall image diagnostic quality, conspicuity of the zonal anatomy and delineation of pathologies of the uterus and cervix, presence of artefacts, and of fluid in the pouch of Douglas (Wilcoxon signed rank test). Signal-to noise ratios (SNRs) and contrast-to-noise ratios (CNRs) were measured for the myometrium versus the rectus abdominis muscle (Student's t-test). RESULTS: BLADE significantly (p < 0.0001) reduced motion and ghosting artefacts and showed improved conspicuity (p = 0.3/0.24), but overall image quality did not differ significantly (inter-observer agreement BLADE κ = 0.89; TSE κ = 0.84). In the majority of cases (53.2 % vs 59.6 %, respectively, κ = 0.82) radiologists preferred conventional TSE due to better image contrast (p < 0.0001) and visibility of free pelvic fluid (p ≤ 0.0001). SNR (TSE 57.5 ± 37.7; BLADE 16.6 ± 12.2) and CNR (TSE 40.4 ± 33.5; BLADE 7.2 ± 8.8) were significantly higher on conventional TSE (p < 0.0001). CONCLUSIONS: Although BLADE reduces motion artefacts and provides a clearer delineation of uterine zonal anatomy compared with conventional TSE, this comes at the expense of overall contrast. MAIN MESSAGES: • Use of BLADE may reduce T2 contrast and thus visibility of free pelvic fluid or cystic structures • Non-Cartesian sampling of k-space such as BLADE is beneficial due to less motion sensitivity • BLADE provides clearer delineation and conspicuity of uterine zonal anatomy on pelvic MRIs.

MRI of the female pelvis: a possible pitfall in the differentiation of haemorrhagic vs. fatty lesions using fat saturated sequences with inversion recovery.

The use of fat-saturated techniques should be an integral part of the work-up of any T1-hyperintense structure in the female pelvis for tissue characterization and for differentiation of a fat-containing ovarian mature teratoma from a haemorrhagic lesion. Two cases with haematocolpos and haematometra are presented, respectively. The haemorrhagic content showed high signal both on T1- and T2-weighted images, whereas an unexpected signal decrease in the fat-saturated T2-weighted inversion-recovery sequence was encountered. This unspecific suppression of signal in tissues with similar T1 relaxation times as fat can lead to a diagnostic pitfall both in T1- and T2-weighted STIR pulse sequences. Furthermore, a loss of signal on T2-weighting may also be due to the phenomenon of "T2-shading" in T1-bright ovarian endometrioma. Therefore, the fat-specific spectral fat-saturation of T1-weighted images is strongly recommended for tissue characterization in gynaecological disease.